This invention relates to a network management device and, more particularly, to a network management device for managing a plurality of network elements such as an ATM switch, transmitting unit, router, bridge and computer interconnected by a communication network. More specifically, the invention relates to network management device capable of being utilized in the field of network management operations such as network management by the operator of an information communications network and network management within an enterprise.
Raising the working efficiency of operators managing network domains and improving service to network end users are common problems involved in network management systems. The present invention likewise appertains to the services field, specifically an improvement in the efficiency of network management operations and the presentation of traffic status to end users. These activities are being forwarded in the same field internationally by network standardization agencies, such as the ITU-T and ISO, which have many participating network operators and vendors of network element equipment.
It is required that a network management device acquire management data from the network element side when the apparatus starts up and at the time of resumption of operation which accompanies recovery from interruption of a session with a network element. It is also required that management data be acquired periodically from the side of the network elements after start-up/resumption of operation in order to assure coordination of data. Conventional network management is so adapted as to accept and execute operations relating to network management after all management data has been acquired from each of the network elements at start-up or resumption of operation of the network management device. In other words, the conventional network management device cannot accept and execute operations relating to network management before the acquisition of all management data is completed.
In a small-scale, simple network management device, it is required to grasp only a limited amount of management data, such as the network addresses allocated to the network elements and the status of the line connections. Consequently, the waiting time until an operation is executable is short and the quantity of management data is small. This means that problems relating to performance and data preservation capacity are comparatively few, and a large number of such network management device are available, as seen in SNMP (Simple Network Management Protocol) products such as Hewlett-Packard's Open View and Sun Microsystems's Sun Net Manager. Similarly, there are many available products for ascertaining the quantity of data that passes through a physical router or gateway owing to the importance of traffic management relating to networks.
In a case where a large-scale network typified by an ATM network is to be managed, the network elements are themselves large in scale and highly complex, the management data held within each of the network elements is of many kinds and of large quantity and the number of network elements dealt with is very large. In a network management device which deals with the management data involving a group of such numerous large-scale, multifarious network elements, there are problems relating to processing time for acquisition of the large quantity of management data held by the network elements and data capacity required by a secondary medium for saving data. More specifically, at start-up of the network management device or at recovery following the interruption of a session, the network management device requires an extended period of time to acquire all management data and the time necessary to wait until network management (operation) can be executed is prolonged. Another problem is that a large-capacity storage device is necessary. A session here means a connection linking applications in OSI Layer Five. Tasks such as control for sending and receiving data and synchronization control are carried out upon setting the session.
Further, in a large-scale network such as an ATM network, role sharing by the network management device and billing apparatus are clearly defined. Information relating to traffic management, such as the quantity of cells passed or the quantity of cells lost or whether a call has been established or not, and the names of the end users are preserved independently in each apparatus without being correlated. As a result, traffic data cannot be handled directly on a per-user basis within the network management device. In other words, a problem with the conventional network management device is that a network end user (subscriber) cannot be designated and the traffic data concerning this user cannot be handled. Though an attempt has been made to establish correspondence between the network management device and the billing system, this inevitably leads to new problems, such as an increase in the quantity of traffic data handled by the network management device, poorer performance and an increase in the capacity required for the data storage medium.
A network user has a need to refer to the traffic status of one's own apparatus on the network for the purpose of performing a planned augmentation of the network or in order to reduce cost by reconsidering the mode of operation. In order to accomplish this, it would be convenient if a traffic characteristic required by the end user could be created and supplied to the end user at an appropriate time.